A substrate, such as a semiconductor wafer, is manufactured by cutting an ingot formed of, for example, silicon. An unintended impurity element sometimes admixes in a local region of a substrate surface due to, for example, segregation and admixture with a foreign substance when the ingot is manufactured. Accordingly, various analysis apparatuses that perform, for example, entire surface analysis, edge analysis, and local analysis, are used to specify the impurity element included in the acquired substrate and a present position of the impurity element. As examples of an apparatus that performs the entire surface analysis to the substrate, out of these apparatuses, apparatuses including etching means that etches a wafer formed of, for example, silicon, and analysis means that analyzes an impurity element in an etchant, have been known. These apparatuses for entire surface analysis collectively analyze the impurity element included in the entire substrate surface. Thus, when the impurity element is present only at a part of the substrate, such as an edge portion or a local region portion, it is unknown where the impurity element is present on the substrate. When an accurate contamination position of the impurity element has not been ascertained, a position to which the local analysis is performed cannot be determined, and a distribution condition of the impurity element cannot be specified.
Accordingly, as examples of an analysis apparatus that conveniently specifies the distribution condition of the impurity element on the substrate prior to the local analysis, a total reflection X-ray fluorescence spectrometry apparatus, a secondary ion mass spectrometry (SIMS) apparatus, and an apparatus with photoluminescence have been known. For example, a total reflection X-ray fluorescence spectrometry apparatus described in Patent Document 1 can nondestructively, conveniently detect in-plane arrangement of an impurity element.
Here, in substrate analysis of, for example, a semiconductor wafer, a semiconductor device with a substrate is required to improve element performance and yield for mass production of a device miniaturized with high precision. Accordingly, there is a demand for specifying even a contamination source minute in quantity, desirously in terms of the substrate to be a raw material of these devices. Thus, a substrate analysis apparatus is required to have high precision necessary for detecting a local impurity element minute in quantity included in a substrate. However, the total reflection X-ray fluorescence spectrometry apparatus can nondestructively perform convenient analysis, but sometimes fails to detect presence of an impurity element when the abundance of the impurity element included in a substrate is minute in quantity. Additionally, only limited types of impurity elements can be measured. SIMS can perform local analysis, but fails to detect an impurity element minute in quantity similarly to the total reflection X-ray fluorescence spectrometry apparatus. Specifically, the concentration of an impurity element detectable by total reflection X-ray fluorescence spectrometry (TRXRF) is in a range from 1010 to 1012 atoms/cm2. The concentration of an impurity element detectable by the SIMS is in a range from 109 to 1010 atoms/cm2.
An example of an analysis apparatus capable of performing analysis with high precision even when the abundance of an impurity element included on a substrate is minute in quantity, includes an inductively coupled plasma mass spectrometry (ICP-MS) apparatus. ICP-MS can detect, for example, trace contamination at sub-ppt level (pg/mL). Additionally, when a substrate surface includes a plurality of impurity elements, the ICP-MS can further specify the types of the impurity elements and the abundance of each of the elements. As described above, when an impurity element locally included in a substrate surface is analyzed by use of the ICP-MS, for example, analysis in which a protective film adheres to portions except a local region to be analyzed (e.g., refer to Patent Document 2) or apparatuses each that make vapor of etching gas for etching a substrate come in contact (e.g., refer to Patent Documents 3 and 4) can be applied.
In analysis with the ICP-MS, an apparatus that has adopted a nozzle for substrate analysis and collects an impurity element present on a substrate with analysis liquid minute in quantity as much as possible, has been known, as in an apparatus in Patent Document 4. An example of the nozzle for substrate analysis is a nozzle for substrate analysis illustrated in FIG. 5 (e.g., refer to Patent Document 5). In FIG. 5, the nozzle for substrate analysis 500 supplies analysis liquid supplied to an analysis liquid vessel 510, to a substrate W through an analysis-liquid supply pipe 520 so that surface tension can retain analysis liquid D minute in quantity at a centroclinal nozzle end portion 550. Accordingly, retaining the analysis liquid minute in quantity allows a contaminant on the substrate to be collected.